Debt - Schedule of Securitization Notes Outstanding (Details) - Mortgage loans $ in Millions	Mar. 31, 2022 USD ($)
Class A-1 Notes | Ajax Mortgage Loan Trust 2019-D/ July 2019
Debt Instrument [Line Items]
Original Principal	$ 140.4
Interest Rate	2.96%
Class A-1 Notes | Ajax Mortgage Loan Trust 2019-F/ November 2019
Debt Instrument [Line Items]
Original Principal	$ 110.1
Interest Rate	2.86%
Class A-1 Notes | Ajax Mortgage Loan Trust 2020-B/ August 2020
Debt Instrument [Line Items]
Original Principal	$ 97.2
Interest Rate	1.70%
Class A-1 Notes | Ajax Mortgage Loan Trust 2021-A/ January 2021
Debt Instrument [Line Items]
Original Principal	$ 146.2
Interest Rate	1.07%
Class A-2 Notes | Ajax Mortgage Loan Trust 2019-D/ July 2019
Debt Instrument [Line Items]
Original Principal	$ 6.1
Interest Rate	3.50%
Class A-2 Notes | Ajax Mortgage Loan Trust 2019-F/ November 2019
Debt Instrument [Line Items]
Original Principal	$ 12.5
Interest Rate	3.50%
Class A-2 Notes | Ajax Mortgage Loan Trust 2020-B/ August 2020
Debt Instrument [Line Items]
Original Principal	$ 17.3
Interest Rate	2.86%
Class A-2 Notes | Ajax Mortgage Loan Trust 2021-A/ January 2021
Debt Instrument [Line Items]
Original Principal	$ 21.1
Interest Rate	2.35%
Class A-3 Notes | Ajax Mortgage Loan Trust 2019-D/ July 2019
Debt Instrument [Line Items]
Original Principal	$ 10.1
Interest Rate	3.50%
Class A-3 Notes | Ajax Mortgage Loan Trust 2019-F/ November 2019
Debt Instrument [Line Items]
Original Principal	$ 5.1
Interest Rate	3.50%
Class M1 Notes | Ajax Mortgage Loan Trust 2019-D/ July 2019
Debt Instrument [Line Items]
Original Principal	$ 9.3
Interest Rate	3.50%
Class M1 Notes | Ajax Mortgage Loan Trust 2019-F/ November 2019
Debt Instrument [Line Items]
Original Principal	$ 6.1
Interest Rate	3.50%
Class M1 Notes | Ajax Mortgage Loan Trust 2020-B/ August 2020
Debt Instrument [Line Items]
Original Principal	$ 7.3
Interest Rate	3.70%
Class M1 Notes | Ajax Mortgage Loan Trust 2021-A/ January 2021
Debt Instrument [Line Items]
Original Principal	$ 7.8
Interest Rate	3.15%
Class B 1 Notes | Ajax Mortgage Loan Trust 2019-D/ July 2019
Debt Instrument [Line Items]
Original Principal	$ 7.5
Interest Rate	3.50%
Class B 1 Notes | Ajax Mortgage Loan Trust 2019-F/ November 2019
Debt Instrument [Line Items]
Original Principal	$ 11.5
Interest Rate	3.50%
Class B 1 Notes | Ajax Mortgage Loan Trust 2020-B/ August 2020
Debt Instrument [Line Items]
Original Principal	$ 5.9
Interest Rate	3.70%
Class B 1 Notes | Ajax Mortgage Loan Trust 2021-A/ January 2021
Debt Instrument [Line Items]
Original Principal	$ 5.0
Interest Rate	3.80%
Class B 2 Notes | Ajax Mortgage Loan Trust 2019-D/ July 2019
Debt Instrument [Line Items]
Original Principal	$ 7.1
Class B 2 Notes | Ajax Mortgage Loan Trust 2019-F/ November 2019
Debt Instrument [Line Items]
Original Principal	10.4
Class B 2 Notes | Ajax Mortgage Loan Trust 2020-B/ August 2020
Debt Instrument [Line Items]
Original Principal	5.1
Class B 2 Notes | Ajax Mortgage Loan Trust 2021-A/ January 2021
Debt Instrument [Line Items]
Original Principal	5.0
Class B-3 Notes | Ajax Mortgage Loan Trust 2019-D/ July 2019
Debt Instrument [Line Items]
Original Principal	12.8
Class B-3 Notes | Ajax Mortgage Loan Trust 2019-F/ November 2019
Debt Instrument [Line Items]
Original Principal	15.1
Class B-3 Notes | Ajax Mortgage Loan Trust 2020-B/ August 2020
Debt Instrument [Line Items]
Original Principal	23.6
Class B-3 Notes | Ajax Mortgage Loan Trust 2021-A/ January 2021
Debt Instrument [Line Items]
Original Principal	$ 21.5
Deferred issuance costs | Ajax Mortgage Loan Trust 2019-D/ July 2019
Debt Instrument [Line Items]
Interest Rate	0.00%
Deferred issuance costs	$ (2.7)
Deferred issuance costs | Ajax Mortgage Loan Trust 2019-F/ November 2019
Debt Instrument [Line Items]
Interest Rate	0.00%
Deferred issuance costs	$ (1.8)
Deferred issuance costs | Ajax Mortgage Loan Trust 2020-B/ August 2020
Debt Instrument [Line Items]
Interest Rate	0.00%
Deferred issuance costs	$ (1.8)
Deferred issuance costs | Ajax Mortgage Loan Trust 2021-A/ January 2021
Debt Instrument [Line Items]
Interest Rate	0.00%
Deferred issuance costs	$ (2.5)
Deferred issuance costs | Ajax Mortgage Loan Trust 2021-B/ February 2021
Debt Instrument [Line Items]
Interest Rate	0.00%
Deferred issuance costs	$ (4.3)
Class A Notes | Ajax Mortgage Loan Trust 2021-B/ February 2021
Debt Instrument [Line Items]
Original Principal	$ 215.9
Interest Rate	2.24%
Class B Notes | Ajax Mortgage Loan Trust 2021-B/ February 2021
Debt Instrument [Line Items]
Original Principal	$ 20.2
Interest Rate	4.00%